SAN DIEGO -- The bothersome right elbow of Mets pitcher Jenrry Mejia flared up again during Saturday night's 8-2 loss to the Padres, forcing the righthander to leave the game in the fourth inning.

Though the Mets remain confident that the pain in Mejia's elbow stems from previously discovered bone chips and not from a yet-undetected structural issue within his elbow, it's unclear whether the 23-year-old will pitch again this season.

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"I wouldn't expect him to pitch any time until he's seen again by the doctor,'' general manager Sandy Alderson said.

If Mejia is forced to miss time, it will further stretch an already thin starting rotation. Earlier in the road trip, righthander Jeremy Hefner was diagnosed with a partial tear of a ligament in his right elbow that might require Tommy John surgery.

The Mets had gone to a six-man rotation to keep Matt Harvey and Zack Wheeler within their innings limits for the season, but injuries forced them to scrap the alignment.

Alderson said the team expects to make a roster move before Sunday's series finale. The Mets could turn to prospects such as Rafael Montero to help fill the void, though Alderson recently said the organization's young pitchers are hitting innings limits of their own.

Flareups have been a clear risk for Mejia, who decided against surgery so he could pitch this season. He has dealt with an elbow issue since spring training but has pitched well since making his big- league return July 26. He fought through pain during a start against the Marlins.

Entering Saturday night's game, Mejia was 1-2 with a 2.22 ERA in five starts. He allowed one run in three innings, striking out five and walking one, before he was forced to depart.

"I don't want to keep pitching with that because I was starting to throw some balls and I want to pitch good,'' said Mejia, who winced after throwing his final pitch to Logan Forsythe in the fourth. "But this bothered me a lot today, more than Miami.''

Flores back in lineupRookie third baseman Wilmer Flores returned to the starting lineup. For four games, he had been limited to a single pinch-hitting appearance after spraining his right ankle in Monday's loss to the Dodgers.

Baby BuckMets catcher John Buck welcomed a new son Saturday. He was in the first day of a three-day paternity leave to spend time with Bentley Ryan Buck in New York and is expected to rejoin the team Tuesday.